Spectator Exciton Effects in Nanocrystals III: Unveiling the Stimulated Emission Cross Section in Quantum Confined CsPbBr Nanocrystals.

Quantifying stimulated emission in semiconductor nanocrystals (NCs) remains challenging due to masking of its effects on pump-probe spectra by excited state absorption and ground state bleaching signals. The absence of this defining photophysical parameter in turn impedes assignment of band edge electronic structure in many of these important fluorophores. Here we employ a generally applicable 3-pulse ultrafast spectroscopic method coined the "Spectator Exciton" (SX) approach to measure stimulated-emission efficiency in quantum confined inorganic perovskite CsPbBr NCs, the band edge electronic structure of which is the subject of lively ongoing debate.

Fluorescent metal nanoclusters: prospects for photoinduced electron transfer and energy harvesting.

Research on noble metal nanoclusters (MNCs) (elements with filled electron d-bands) is progressing forward because of the extensive and extraordinary chemical, optical, and physical properties of these materials. Because of the ultrasmall size of the MNCs (typically within 1-3 nm), they can be applied in areas of nearly all possible scientific domains. The greatest advantage of MNCs is the tunability that can be imposed, not only on their structures, but also on their chemical, physical, and biological properties.

Hydrophobic Chain-Induced Conversion of Three-Dimensional Perovskite Nanocrystals to Gold Nanocluster-Grafted Two-Dimensional Platelets for Photoinduced Electron Transfer Substrate Formulation.

Considering the augmentation of new generation energy harvesting devices and applications of electron-hole separation therein, conversion of 3D cubic CsPbBr perovskite nanocrystals into 2D-platelets through ligand-ligand hydrophobic interactions has been conceived here. Cationic surfactants with various chain length coated the gold nanoclusters (AuNCs) that interact with oleic acid (OA) and oleylamine (OAm) coated 3D CsPbBr nanocrystals to disintegrate the crystallinity of the perovskites and reformation of AuNC-grafted 2D-platelets of unusually large size. The planar perovskite-derivatives act as an exciton donor to the embedded AuNCs through photoinduced electron transfer (PET).

Ultrafast insights into full-colour light-emitting C-Dots.

Designing carbon dots (C-Dots) in a controlled way requires a profound understanding of their photophysical properties, such as the origin of their fluorescence and excitation wavelength-dependent emission properties, which has been a perennial problem in the last few decades. Herein, we synthesized three different C-Dots (blue, green, and red-emitting C-Dots) from the same starting materials a hydrothermal method and separated them by silica column chromatography. All the purified C-Dots exhibited three different emission maxima after a certain range of different excitations, showing a high optical uniformity in their emission properties.

Long-range light-modulated charge transport across the molecular heterostructure doped protein biopolymers.

Biological electron transfer (ET) across proteins is ubiquitous, such as the notable photosynthesis example, where light-induced charge separation takes place within the reaction center, followed by sequential ET intramolecular cofactors within the protein. Far from biology, carbon dots (C-Dots) with their unique optoelectronic properties can be considered as game-changers for next-generation advanced technologies. Here, we use C-Dots for making heterostructure (HS) configurations by conjugating them to a natural ET mediator, the hemin molecule, thus making an electron donor-acceptor system.

Photosensitization Dynamics of Stable Copper Nanoclusters inside the Aqueous Core of Reverse Micelles with Different Pool Sizes.

The perennial problem of instability of fluorescent copper nanoclusters (Cu NCs), stemming principally from aerial oxidation, has prevented their vivid usage in energy harvesting compared to the other metal NCs. However, replacement of the much expensive metal NCs with the cheaper Cu NCs is desirable if the functions are met with. Although thiolate protection of Cu NCs could bring some stability to them, appreciably decentlystable Cu NCs were produced inside the aqueous core of reverse micelles (RMs).

Silver nanoclusters are probably better and cheaper protecting agents for protein from UVC radiation compared to gold nanoclusters.

It has been shown experimentally that the albumin proteins can be significantly protected by silver nanoclusters (AgNCs) from the adverse effects of UVC radiation. The parameters have been compared with the effects of gold nanoclusters (AuNCs) under similar circumstances. The protection depends on the absorptive power of the metal cluster.

Correction to "Application of Photoinduced Electron Transfer with Copper Nanoclusters toward Finding Characteristics of Protein Pockets".

[This corrects the article DOI: 10.1021/acsomega.8b03213.

Application of Photoinduced Electron Transfer with Copper Nanoclusters toward Finding Characteristics of Protein Pockets.

Proteins possess various domains and subdomain pockets with varying hydrophobicity/hydrophilicity. The local polarities of these domains play a major role in oxidation-reduction-based biological processes. Herein, we have synthesized ultrasmall fluorescent copper nanoclusters (Cu NCs) that are directed to bind to the different domain-specific pockets of the model protein bovine serum albumins (BSA).

Gold Nanocluster-Grafted Cyclodextrin Suprastructures: Formation of Nanospheres to Nanocubes with Intriguing Photophysics.

Glutathione (GSH)-coated gold nanoclusters (Au NCs) were synthesized in aqueous acidic medium. On deprotonation of the carboxyl groups of the GSH molecules under alkaline condition, the anionic ends react with the added cationic surfactant molecules to convert the Au NCs hydrophobic, resulting in loss of fluorescence due to apparent insolubility in water. The fluorescence is revived by adding cyclodextrins (CDs) that encapsulate the protruding hydrophobic tails of the surfactant molecules surrounding the GSH-coated Au NCs.